Fuel Cell Mechanical Components

ABSTRACT

A modular fuel cell system includes a base, at least four power modules arranged in a row on the base, and a fuel processing module and power conditioning module arranged on at least one end of the row on the base. Each power module includes a separate cabinet which contains at least one fuel cell stack located in a hot box. The power modules are electrically and fluidly connected to the at least one fuel processing and power conditioning modules through the base.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/845,685, filed Mar. 18, 2013, which is acontinuation of U.S. patent application Ser. No. 13/242,194, filed Sep.23, 2011, now U.S. Pat. No. 8,440,362, which claims priority to U.S.Provisional Application No. 61/386,257, filed on Sep. 24, 2010, theentire contents of both applications are hereby incorporated byreference to provide continuity of disclosure.

BACKGROUND

The present invention is directed generally to fuel cell systems andspecifically to mechanical components of the fuel cell systems.

Rapid and inexpensive installation can help to increase the prevalenceof fuel cell systems. Installation costs for pour in place customdesigned concrete pads, which generally require trenching for plumbingand electrical lines, can become prohibitive. Installation time is alsoa problem in the case of most sites since concrete pours and trenchesgenerally require one or more building permits and building inspectorreviews.

Furthermore, stationary fuel cell systems may be installed in locationwhere the cost of real estate is quite high or the available space islimited (e.g., a loading dock, a narrow alley or space betweenbuildings, etc.). The fuel cell system installation should have a highutilization of available space. When a considerable amount of stand-offspace is required for access to the system via doors and the like,installation real estate costs increase significantly.

When the number of fuel cell systems to be installed on a siteincreases, one problem which generally arises is that stand-off spacebetween these systems is required (to allow for maintenance of one unitor the other unit). The space between systems is lost in terms of it'spotential to be used by the customer of the fuel cell system.

In the case of some fuel cell system designs, these problems areresolved by increasing the overall capacity of the monolithic systemdesign. However, this creates new challenges as the size and weight ofthe concrete pad required increases. Therefore, this strategy tends toincrease the system installation time. Furthermore, as the minimum sizeof the system increases, the fault tolerance of the design is reduced.

The fuel cell stacks or columns of the fuel cell systems are usuallylocated in hot boxes (i.e., thermally insulated containers). The hotboxes of existing large stationary fuel cell systems are housed incabinets, housings or enclosures. The terms cabinet, enclosure andhousing are used interchangeably herein. The cabinets are usually madefrom metal. The metal is painted with either automotive or industrialpowder coat paint, which is susceptible to scratching, denting andcorrosion. Most of these cabinets are similar to current industrial HVACequipment cabinets.

SUMMARY

A modular fuel cell system includes a base, at least four power modulesarranged in a row on the base, and a fuel processing module and powerconditioning module arranged on at least one end of the row on the base.Each power module includes a separate cabinet which contains at leastone fuel cell stack located in a hot box. The power modules areelectrically and fluidly connected to the at least one fuel processingand power conditioning modules through the base.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a modular fuel cell system enclosureaccording to an exemplary embodiment.

FIG. 2 is an isometric view of a module of the fuel cell systemenclosure of FIG. 1 according to an exemplary embodiment.

FIG. 3 is an isometric view of a portion of a pre-cast base for the fuelcell enclosure of FIG. 1 according to an exemplary embodiment. FIG. 3Ais an isometric view of a portion of a modular pre-cast base.

FIG. 4 is an isometric view of a door for the module of FIG. 2 in afirst open configuration according to an exemplary embodiment.

FIG. 5 is a cross-section view of a door for the module of FIG. 2 takenalong line 5-5 showing an airflow through the door according to oneexemplary embodiment.

FIG. 6 is a cross-section view of a door for the module of FIG. 2 takenalong line 6-6 showing an airflow through the door according to anotherexemplary embodiment.

FIG. 7 is a side view of the module of FIG. 2 with the side wallremoved, showing the door in a closed position according to an exemplaryembodiment.

FIG. 8 is a side view of the module of FIG. 2 with the side wallremoved, showing the door in an open position according to an exemplaryembodiment.

FIG. 9 is a side view of the module of FIG. 2 with the side wallremoved, showing the door in a closed position with springs to bias thedoor in the closed position according to an exemplary embodiment.

FIG. 10 is a front view of the module of FIG. 2 with the outer doorpanel removed, showing a latch mechanism in a locked position accordingto an exemplary embodiment.

FIG. 11 is a front view of the module of FIG. 2 with the outer doorpanel removed, showing a latch mechanism in an unlocked positionaccording to an exemplary embodiment.

FIG. 12 is an isometric view showing a location of a hot box inside themodule enclosure with the enclosure door removed.

FIGS. 13-16 are isometric views of the module of FIG. 12 showing the hotbox being removed from the enclosure onto a pallet according to anexemplary embodiment.

FIG. 17 is an isometric view of rotatable desulfurizer assembly for thefuel cell system of FIG. 1 according to an exemplary embodiment.

FIG. 18 is an isometric view of a canister for the desulfurizer assemblyof FIG. 17 according to an exemplary embodiment.

FIG. 19 is a top view of the canister of FIG. 18 according to anexemplary embodiment.

FIG. 20 is an isometric view of the canister of FIG. 18 with the topremoved to show internal chambers according to an exemplary embodiment.

FIG. 21 is a top view of the canister of FIG. 18 with the top removed toshow internal chambers according to an exemplary embodiment.

FIG. 22 is a schematic diagram showing plumbing connections for thecanisters of the rotatable desulfurizer assembly of FIG. 17 according toan exemplary embodiment.

FIGS. 23A-C illustrate (A) an alternative removal tool; (B) anembodiment of a removable support and (C) another view of the removablesupport illustrated in 23(B).

DETAILED DESCRIPTION

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention as claimed.

Modular System

Referring to FIG. 1, a modular fuel cell system enclosure 10 is shownaccording to an exemplary embodiment. The modular system may containmodules and components described in U.S. patent application Ser. No.11/656,006, filed on Jan. 22, 2007, and incorporated herein by referencein its entirety. The modular design of the fuel cell system enclosure 10provides flexible system installation and operation. Modules allowscaling of installed generating capacity, reliable generation of power,flexibility of fuel processing, and flexibility of power output voltagesand frequencies with a single design set. The modular design results inan “always on” unit with very high availability and reliability. Thisdesign also provides an easy means of scale up and meets specificrequirements of customer's installations. The modular design also allowsthe use of available fuels and required voltages and frequencies whichmay vary by customer and/or by geographic region.

The modular fuel cell system enclosure 10 includes at least one(preferably more than one or plurality) of power modules 12, one or morefuel input (i.e., fuel processing) modules 16, and one or more powerconditioning (i.e., electrical output) modules 18. In embodiments, thepower conditioning modules 18 are configured to deliver direct current(DC). In alternative embodiments, the power conditioning modules 18 areconfigured to deliver alternating current (AC). In these embodiments,the power condition modules include a mechanism to convert DC to AC,such as an inverter. For example, the system enclosure may include anydesired number of modules, such as 2-30 power modules, for example 3-12power modules, such as 6-12 modules. FIG. 1 illustrates a systemenclosure 10 containing six power modules 12 (one row of six modulesstacked side to side), one fuel processing module 16, and one powerconditioning module 18 on a common base 20. Each module 12, 16, 18 maycomprise its own cabinet. Alternatively, as will be described in moredetail below, modules 16 and 18 may be combined into a singleinput/output module 14 located in one cabinet. While one row of powermodules 12 is shown, the system may comprise more than one row ofmodules 12. For example, the system may comprise two rows of powermodules arranged back to back/end to end.

Each power module 12 is configured to house one or more hot boxes 13.Each hot box contains one or more stacks or columns of fuel cells (notshown for clarity), such as one or more stacks or columns of solid oxidefuel cells having a ceramic oxide electrolyte separated by conductiveinterconnect plates. Other fuel cell types, such as PEM, moltencarbonate, phosphoric acid, etc. may also be used.

The fuel cell stacks may comprise externally and/or internallymanifolded stacks. For example, the stacks may be internally manifoldedfor fuel and air with fuel and air risers extending through openings inthe fuel cell layers and/or in the interconnect plates between the fuelcells.

Alternatively, the fuel cell stacks may be internally manifolded forfuel and externally manifolded for air, where only the fuel inlet andexhaust risers extend through openings in the fuel cell layers and/or inthe interconnect plates between the fuel cells, as described in U.S.Pat. No. 7,713,649, which is incorporated herein by reference in itsentirety. The fuel cells may have a cross flow (where air and fuel flowroughly perpendicular to each other on opposite sides of the electrolytein each fuel cell), counter flow parallel (where air and fuel flowroughly parallel to each other but in opposite directions on oppositesides of the electrolyte in each fuel cell) or co-flow parallel (whereair and fuel flow roughly parallel to each other in the same directionon opposite sides of the electrolyte in each fuel cell) configuration.

The modular fuel cell system enclosure 10 also contains one or moreinput or fuel processing modules 16. This module 16 includes a cabinetwhich contains the components used for pre-processing of fuel, such asadsorption beds (e.g., desulfurizer and/or other impurity adsorption)beds. The fuel processing modules 16 may be designed to processdifferent types of fuel. For example, a diesel fuel processing module, anatural gas fuel processing module, and an ethanol fuel processingmodule may be provided in the same or in separate cabinets. A differentbed composition tailored for a particular fuel may be provided in eachmodule. The processing module(s) 16 may process at least one of thefollowing fuels selected from natural gas provided from a pipeline,compressed natural gas, methane, propane, liquid petroleum gas,gasoline, diesel, home heating oil, kerosene, JP-5, JP-8, aviation fuel,hydrogen, ammonia, ethanol, methanol, syn-gas, bio-gas, bio-diesel andother suitable hydrocarbon or hydrogen containing fuels. If desired, areformer 17 may be located in the fuel processing module 16.Alternatively, if it is desirable to thermally integrate the reformer 17with the fuel cell stack(s), then a separate reformer 17 may be locatedin each hot box 13 in a respective power module 12. Furthermore, ifinternally reforming fuel cells are used, then an external reformer 17may be omitted entirely.

The modular fuel cell system enclosure 10 also contains one or morepower conditioning modules 18. The power conditioning module 18 includesa cabinet which contains the components for converting the fuel cellstack generated DC power to AC power (e.g., DC/DC and DC/AC convertersdescribed in U.S. Pat. No. 7,705,490, incorporated herein by referencein its entirety), electrical connectors for AC power output to the grid,circuits for managing electrical transients, a system controller (e.g.,a computer or dedicated control logic device or circuit). The powerconditioning module 18 may be designed to convert DC power from the fuelcell modules to different AC voltages and frequencies. Designs for 208V,60 Hz; 480V, 60 Hz; 415V, 50 Hz and other common voltages andfrequencies may be provided.

The fuel processing module 16 and the power conditioning module 18 maybe housed in one input/output cabinet 14. If a single input/outputcabinet 14 is provided, then modules 16 and 18 may be located vertically(e.g., power conditioning module 18 components above the fuel processingmodule 16 desulfurizer canisters/beds) or side by side in the cabinet14.

As shown in one exemplary embodiment in FIG. 1, one input/output cabinet14 is provided for one row of six power modules 12, which are arrangedlinearly side to side on one side of the input/output module 14. The rowof modules may be positioned, for example, adjacent to a building forwhich the system provides power (e.g., with the backs of the cabinets ofthe modules facing the building wall). While one row of power modules 12is shown, the system may comprise more than one row of modules 12. Forexample, as noted above, the system may comprise two rows of powermodules stacked back to back.

The linear array of power modules 12 is readily scaled. For example,more or fewer power modules 12 may be provided depending on the powerneeds of the building or other facility serviced by the fuel cell system10. The power modules 12 and input/output modules 14 may also beprovided in other ratios. For example, in other exemplary embodiments,more or fewer power modules 12 may be provided adjacent to theinput/output module 14. Further, the support functions could be servedby more than one input/output module 14 (e.g., with a separate fuelprocessing module 16 and power conditioning module 18 cabinets).Additionally, while in the preferred embodiment, the input/output module14 is at the end of the row of power modules 12, it could also belocated in the center of a row power modules 12.

The modular fuel cell system enclosure 10 may be configured in a way toease servicing of the system. All of the routinely or high servicedcomponents (such as the consumable components) may be placed in a singlemodule to reduce amount of time required for the service person. Forexample, a purge gas (optional) and desulfurizer material for a naturalgas fueled system may be placed in a single module (e.g., a fuelprocessing module 16 or a combined input/output module 14 cabinet). Thiswould be the only module cabinet accessed during routine maintenance.Thus, each module 12, 14, 16, and 18 may be serviced, repaired orremoved from the system without opening the other module cabinets andwithout servicing, repairing or removing the other modules.

For example, as described above, the enclosure 10 can include multiplepower modules 12. When at least one power module 12 is taken off line(i.e., no power is generated by the stacks in the hot box 13 in the offline module 12), the remaining power modules 12, the fuel processingmodule 16 and the power conditioning module 18 (or the combinedinput/output module 14) are not taken off line. Furthermore, the fuelcell enclosure 10 may contain more than one of each type of module 12,14, 16, or 18. When at least one module of a particular type is takenoff line, the remaining modules of the same type are not taken off line.

Thus, in a system comprising a plurality of modules, each of the modules12, 14, 16, or 18 may be electrically disconnected, removed from thefuel cell enclosure 10 and/or serviced or repaired without stopping anoperation of the other modules in the system, allowing the fuel cellsystem to continue to generate electricity. The entire fuel cell systemdoes not have to be shut down if one stack of fuel cells in one hot box13 malfunctions or is taken off line for servicing.

Pre-Cast Base

Referring now to FIG. 3A, a section of a pre-cast base or pad 20 isshown according to an exemplary embodiment, which provides a mountingand support surface for the power modules 12 and input/output module(s)14 of the fuel cell system of FIG. 1. In one embodiment, two or moresuch pre-cast sections are joined to form the base 20 that supports themodules 12 and 14 of the full system. By providing the pre-cast base 20in sections, the overall weight of the structures to be transported,manipulated, and installed is reduced. The base 20 is preferably made ofconcrete or similar material, such as a geopolymer based composition.Alternatively, the base 20 may be made of any other suitable structuralmaterial, such as steel or another metal. The base 20 may be made bycasting the base material into a patterned mold, removing the cast base20 from the mold and then transporting the pre-cast base 20 from thelocation of the mold (e.g., in a base fabrication facility) to thelocation of the fuel cell system (i.e., where the fuel cell system willbe located to generate power). The step of transporting may comprisetransporting the base sections a distance away from the factory, such asat least one kilometer.

FIG. 3B illustrates the pre-cast sections 20 of the modular base.Alignment and assembly of the pre-cast sections 20 may be performed, forexample, with mating male 21 a and female 21 b pins. Other methods mayalso be used, such as jigsaw patterns on the edges of the pre-castsections or with a system of protrusion and slots. In this manner, abase suitable for a large number of power modules 12 may be easilyfabricated from a plurality of smaller pre-cast sections 20. Forexample, a single base may be designed to support two power modules 12.These pre-cast sections 20 may be easily cast and transported. Thepre-cast sections 20 may be assembled on site to create a base suitablefor a power system having 4, 6, 8, 12 or more power modules 12.

Existing fuel cell systems may connect various modules with electricalwires that are run through rubber seal panels that keep the rain out.The hot gasses (e.g., fuel and air inlet and outlet streams) areprovided to and from the fuel cell stacks through conduits, such aspipes and manifolds.

According to an exemplary embodiment, the pre-cast base 20 is formed toinclude channels (e.g. trenches, depressions, slots, etc.) to receiveelectrical bus bar conduits 24, input and output fuel conduits 27 andwater conduit(s) 28 to and from the system and/or between the modules. Afirst channel 22 houses the electrical bus bar 24, which provides busconnections to the power modules 12 and input/output module(s) 14. Asshown in the Figures, the bus bar 24 may be a laminated bus bar with asegmented design or a section of a cable. A second channel 26 houses theheader for fuel supply conduit 27 and the header for the water supplyconduit 28. Quick connects/disconnects couple the conduits 27 and 28 tothe fuel and water inlets in each module 12 and 14, as described forexample in U.S. application Ser. No. 12/458,355, filed on Jul. 8, 2009and incorporated herein by reference in its entirety. By providing thebus bar conduits 24 and fluid conduits 27, 28 in channels in thepre-cast base 20, the fuel cell modules 12 and/or 14 themselves protectthe bus or header connections from the elements. Additional channels maybe formed in the base 20 to house other components, such ascommunication lines, or to provide water drainage features to ensurewater is directed as desired for good system integration. Further, thefirst and second channels 22, 26 and other features of the pre-cast base20 may be formed in a mirrored configuration. In this manner, the systemcan be assembled with plural power modules 12 in a mirroredconfiguration, simplifying assembly and maintenance.

The precast base 20 may include beveled structures to allow the fuelcell modules 12 and 14 to self-align to the pre-cast base 20 andplumbing and wiring structures (e.g. quick connects/disconnects for theconduits 24, 27 and 28). According to one exemplary embodiment, theself-alignment feature may comprise an angled latch mechanism asdescribed in U.S. application Ser. No. 12/458,355, filed on Jul. 8, 2009and incorporated herein by reference in its entirety. In anotherexemplary embodiment, the self alignment feature may comprise a conemounted or integrally formed with the pre-cast base 20, similar to thefeatures described in U.S. application Ser. No. 12/458,355. The cone isconfigured to be received in a corresponding indentation on the base ofthe fuel cell system modules 12 and 14 which to ensure proper alignmentas the modules 12 and 14 are lowered to the base.

Unlike concrete bases that are poured on-site, a pre-cast base 20 caninclude all features necessary for the site installation. The design forthe pre-cast base 20 can be pre-approved by a civil engineer,significantly reducing review time by local authorities when the base 20is installed. The pre-cast base 20 simplifies site preparation andinstallation by eliminating the need for trenching for fuel, water andelectricity during site preparation. However, in an alternativeembodiment, the base 20 with channels may be poured on the site wherethe fuel cell system will operate.

Door Materials And Appearance

Because of the significant size of the fuel cell stack hot boxes, largestationary fuel cell system cabinets have large cabinet doors. The doorsmay be one to three meters tall by one to three meters wide and made ofmetal, such as steel or aluminum. The large dimensions of the doorsresult in higher mechanical loading requirements on the cabinet,increased door weight and increased difficulty of handing the doors.Furthermore, the large doors require a large amount of wasted stand offspace between each cabinet and an adjacent structure (e.g., building,another cabinet, etc.) to allow the side hinged door to swing open.

A conventional door opening mechanism (such as a left or right-sidedhinged mechanism) would leave the opened door in a position that couldhinder access to the inside of the cabinet, especially in a narrowspace, such as an alley, or leave the door in a position that couldexpose it to damage from other doors or equipment. Furthermore, hinginga door from the side could contribute to door-sag from its own weightand dimensions. An additional issue faced when designing a fuel cellcabinet for outdoor operation is the integrity of the weather seal ateach door interface. The seal must be positively assured in order toeliminate the reliability impact of water and foreign material entry tothe cabinet.

Furthermore, the doors may be constructed from many parts due to themultiple functions that a door performs, such as protecting the fuelcell hot box from the environment, providing a thermal barrier betweenthe outside of the hot box and the ambient, housing the air filters,providing mounting locations for latches, hinges, and seals, etc. Thelarge amount of parts may impact the quality and placement accuracy ofthe door.

Referring now to FIG. 4, each of the power modules 12 and input/outputmodules 14 include a door 30 (e.g., hatch, access panel, etc.) to allowthe internal components of the module to be accessed (e.g., formaintenance, repair, replacement, etc.). According to an exemplaryembodiment, the modules 12 and 14 are arranged in a linear array thathas doors 30 only on one face of each cabinet, allowing a continuous rowof systems to be installed abutted against each other at the ends. Thus,the cabinets have doors facing perpendicular to an axis of the modulerow. In this way, the size and capacity of the fuel cell enclosure 10can be adjusted with additional modules 12 or 14 and bases 20 withminimal rearranging needed for existing modules 12 and 14 and bases 20.If desired, the door to module 14 may be on the side rather than on thefront of the cabinet.

According to an exemplary embodiment, the access doors 30 for themodules 12 and 14 are formed of at least one inner portion 32 and atleast one outer portion 34. The inner portion 32 forms a framework forthe door 30 and includes features to allow the door 30 to be coupled tothe module 12 or 14. The outer portion 34 is coupled to the innerportion 32 and provides an outer fascia for the door 30. In a preferredembodiment, the outer portion 34 is formed of a polymeric material andthe inner portion 32 is formed of a metal material.

By forming the outer portion 34 of the door 30 at least partially withpolymeric components, the building and painting costs, overall weight,and exterior heat loading can be reduced and the dent resistance of thedoor 30 can be increased. Flame resistance per UL 746C can be includedfor the material of the outer portion 34 when needed for specificapplications.

In one exemplary embodiment, the entire door 30 is injection molded as asingle structure. The injection molded door 30 incorporates as manyfeatures as possible to reduce total part count, provide mountingpoints, and simplify production of high quality parts. The mold for sucha molded door can be configured to allow two different plastics to beco-injected into the same mold, such that the inner side of the door(i.e., the side which faces into the cabinet when closed) is made from aheat and flame resistant plastic sheet, while the outer side of the dooris made from a plastic sheet that is weather resistant and aestheticallypleasing without possessing the flame and high temperature resistance.An air filter may be located between the inner and outer portions of thedoor.

According to another exemplary embodiment, the door 30 is formed with avacuum thermoforming process. A sheet can first be formed withco-extrusion of two or more plastics that meet UL and cosmeticrequirements. The co-extruded sheet can then be vacuum thermoformed toform the door 30.

Because high temperature fuel cells (e.g. SOFCs) operate at hightemperatures, door 30 may be formed to have materials or features toincrease the flame resistance of the door 30. If there is no risk offlame or extreme heat exposure, then a standard, low cost, color plasticmaterial can be used to form the door 30. If there is a low risk offlame, additives can be mixed with the standard plastic whilemaintaining exterior quality of the door 30. For example, co-injectioncan be used to mold the exterior (e.g., the outer portion 34) using thestandard plastic and the interior (e.g., the inner portion 32) using therequired UL746C flame resistant plastic. A single, co-injection moldwith inserts to allow for needed features can be used to form the door.According to other exemplary embodiments, when flame resistance isneeded per UL746C, the door 30 may feature another type of flameretardant feature on its surface (e.g., a flame retardant coating addedto the inner surface of the door 30; a separate, flexible flameretardant layer such as cloth is provided over the inner surface of thedoor; a separate, rigid flame retardant layer such as an extruded flatplastic; etc.).

The polymer outer portion 34 can be molded or otherwise formed in avariety of colors, eliminating the need for paint. The polymer outerportion 34 may be dent resistant and graffiti resistant. The polymerouter portion 34 may be scratch resistant and any scratches that dooccur will be less visible than similar scratches on a metal body andwill not cause associated corrosion problems. Further, the outer portion34 can include additional parts and features that are integrally molded,such as molded in filter housings, and inserted fasteners to promoteeasier, faster, more accurate assembly of the door 30 and installationof the doors 30 on the modules 12 and 14.

A logo 36 (FIG. 2) may be affixed to or formed during molding of one ormore of the doors 30 of the fuel cell system enclosure 10. This logo 36may be lighted (e.g., by including a backlight behind the logo) tohighlight the operating status of the unit. The logo 36 can be affixedto the door 30 in a manner as to allow the logo 36 to be backlit (e.g.,over an opening in the outer portion 34 of the door 30 containing an LEDor another backlight) when the particular unit or module is operating.

A polymer outer portion 34 can reduce costs by reducing manual labor andmaterial needed for construction of the door 30. Forming the outerportion 34 with a process such as injection molding allows for highlyrepeatability for better fit and easier assembly of the door 30. Apolymer material is lighter than a corresponding part formed of a metalmaterial allowing for easier handling, lifting, and reduced shippingcosts.

Filter Assembly

Fuel system cabinets generally include filtration systems to filterincoming cooling air that passes through the cabinet. In high-dustenvironments, multi-layered filters can quickly become clogged andrequire frequent changes. Pneumatic back flush filters only work whenthe air intake is shut down and generally do not work well constant run,always-on fuel cell systems. Water curtain filters, in which a curtainof falling water removes particles form air passing through the water,requires power and water flow, which complicates the operation of thesystem. Such systems require a water filter for a closed system or aconstant water supply for open systems.

The door 30 may include one or more air filters 40 as shown in FIG. 4.For example, two standard filters 40 may be located over each other in aspace between the inner 32 and outer 34 door 30 portions.

As shown in FIG. 5, the left and/or right edge of the door 30 includesan opening (e.g., vertical intake louver or inlet) 42 to the spacebetween the inner 32 and outer 34 door portions where the filters 40 arelocated. The opening 42 acts as an air inlet into the cabinet of thepower module 12. The air passes through the filters 40 to filter foreignmaterial (e.g., dust, dirt, etc.) from the incoming air. The filteredair is then provided to the inside of the cabinet through an outlet 44in the inner portion 32 of the door 30. Thus, the air filters 40 areprovided between the inlets(s) 42 and the outlet 44. The filtered airacts as the inlet air stream which is blown into the fuel cell stackslocated in the hot box by an air blower located in the cabinet.

The door may further include a rough or initial filtering mechanism,such as one or more perforated screens 46, as shown in FIG. 5. Thescreen(s) 46 are located in the air flow path between the air inlet 42and the filter(s) 40. Each screen 46 may have an “L” shape when viewedfrom the top of the door. By pre-filtering the incoming air, the door 30reduces the amount of dust and other particulates fouling the airfilters 40.

Additional, optional, non-limiting features of the air filtration systemof a door 30 are shown in FIG. 5 according to one exemplary embodiment.FIG. 5 is a top view of the door 30 along line 5-5 in FIG. 2.

Air (shown by arrows in FIG. 5) enters from one or more door sides(e.g., left and/or right edge surfaces of the door) through the inlets42 and immediately enters a larger volume 41 located between the inletsand the screen 46. In other words, the width of the volume 41 is largerthan that of the adjacent inlet 42. This allows the air to expand andslow in the volume 41. As the air slows, dirt, dust and otherparticulate matter suspended in air is allowed to drop down to thebottom of the volume 41 prior to reaching the perforated side screens46. The air then passes through the side perforated screens 46 andenters an inner cavity 45 between door portions 32 and 34 where the airturns about 90 degrees as shown by the arrows in FIG. 5 to move to theplenum in front of the air filter 40. The screens 46 also createturbulence in the air flow. When the air flow becomes more turbulent andturns abruptly, entrained and suspended particulates that passed throughthe perforated screens 46 are caused further to drop out of the air. Airwith reduced foreign material then passes through air filter 40. Thefilter assembly 40 creates an inner vertical baffle. The air filter 40provides final filtration, and filtered air enters the cabinet throughthe outlet 44 in the inner portion of the door.

The outer portion 34 of the door 30 is configured to be hinged outwardrelative to the inner door 32 (see FIG. 4) to aid in rapid and easyservicing of the door filters 40. The hinge may be on the bottom of thedoor 30 such that the outer portion 34 of the door 30 swings downward toexpose the filters 40 for maintenance without opening the inner portion32 of the door 30 to the inside of the module 12 or 14. Thus, thefilters may be serviced or replaced without opening the entire door 30to the cabinet of a module 12.

One or more frame members 38 holding the filters 40 can be configured topivot outward or to allow only the filters 40 to pivot outward as shownin FIG. 4. The frame member 38 and/or filters 40 may be configured topivot outward using a pivot point on the bottom end thereof. The member38 and/or filters 40 may be configured to automatically pivot outwardwhen the outer portion 34 of the door 30 is pivoted outward.Alternatively, the member 38 and/or filters 40 may be pivoted outwardmanually by the operator after the outer portion 34 of the door ispivoted outward. The changing of the door filters 40 is performedwithout breaking the water-tight seal of the inner portion 32 of thedoor assembly 30. Thus, the outer door portion 34 is tilted away, thefilters 40 are lifted out and replaced, and the outer portion 34 isclosed by being swung upwards to be latched to the inner portion of thedoor 32, as shown in FIG. 4.

The shape of the door inlet 42 is preferably such that the air inletarea is not directly visible from the front of the door and the front ofthe module, thereby improving the aesthetic of the appearance of thefuel cell system. At the same time, since the inlet 42 extends along thefull vertical left and right edges of the door 30, inlet pressure dropis diminished, reducing the parasitic power draw of the system. Further,since the air inlets 42 may be located on both the left and right sidesof the door 30, if there is a systematic bias in environmental foreignmaterial (such as may occur with snow or sand drifts or other windblowndebris), one of the two sides will effectively be in the “lee” (i.e.,downstream) of the oncoming wind, and thereby be significantly more freeof foreign material allowing the unit to operate without obstructioneven in severe storm conditions.

The configuration of the door 30 as shown in FIG. 5 has severalnon-limiting advantages. The air passing through the door 30 issignificantly cleaner before it even first enters the filters 40 thanprior art doors. No direct power is consumed to perform the first-stageforeign material removal, achieved by the passive filtering of the airas described above. By reducing the amount of foreign material thatreaches the filters 40, the frequency with which the filters 40 must bechanged is reduced. By extending the life of the filters 40, secondarycosts due to service personnel visits and filter consumables areconsiderably reduced for the fuel cell system.

Intake Louver

Referring now to FIG. 6, a door 30 containing a passive air intakelouver is shown according to an alternative embodiment. The intakelouver contains a plurality of internal baffles 47 which force the airintake provided from the inlet(s) 42 to change direction at least 2times inside the door 30 before reaching the outlet 44. The internalbaffles 47 may be formed, for example, simply with offset opposing rowsof c-channels coupled to the inside of the door 30.

The baffles 47 may comprise strips or rails which are alternativelyattached to the inner 32 and outer 34 portions of the door 30, in aroughly interdigitated arrangement (e.g., with baffles attached toopposite portions 32, 34 of the door overlapping or not overlapping inthe door thickness direction from outer portion 34 to inner portion 32).The baffles 47 may extend the entire or just a part of the verticalheight of the door 30. In general, the baffles 47 may be arranged in anysuitable configuration which prevents the air inlet stream fromtravelling in a straight line from inlet 42 to outlet 44 and forces theair inlet stream to travel a serpentine path from inlet 42 to outlet 44.

The foreign material (dust, sand, mist, etc.) in the air stream hasmomentum which causes it to continue moving forward while the airchanges direction around the baffles 47. The dust and sand collects inthe corners (e.g., at the upstream baffle surface) formed by the baffles47 and drains out of the door through openings 48 in the bottom of thedoor 30. Air with significant reductions of dust and dirt exits thelouver assembly through outlet 44.

The intake louver of FIG. 6 may be used together with the screen 46and/or expansion chamber 41 and/or filter(s) 40 shown in FIG. 5. In thiscase, the air first passes from inlet 42 through expansion chamber 41and/or screen 46 before reaching the baffles 47 of the louver. The airthen passes from the louver filter(s) 40, as shown in FIGS. 4 and 5 andinto the module 12 or 14 through an outlet 44 in the door.Alternatively, the intake louver may be present in a door which lacksone, two or all of the screen 46 and/or expansion chamber 41 and/orfilter(s) 40 shown in FIG. 5.

FIG. 6 depicts two sets of louver structures with air entering from twoinlets 42 on left and right sides of the door 30. However, more than twosets of louver structures may be provided in the door 30 at periodicintervals and more than two inlets 42 may be provided. Furthermore,while the inlets 42 are shown in the front portion 34 of the door 30 inFIG. 6, the inlets 42 may be located in the side (i.e., edge) of thedoor 30 as shown in FIG. 5 in addition to or instead of in the front ofthe door.

Door Assembly

As noted above, because of the significant size of the fuel cell stackhot boxes, large stationary fuel cell system cabinets have large cabinetdoors. The large dimensions of the doors result in higher mechanicalloading requirements on the cabinet, increased door weight and increaseddifficulty of handing the doors. Furthermore, the large doors require alarge amount of wasted stand off space between each cabinet and anadjacent structure (e.g., building, another cabinet, etc.) to allow theside hinged door to swing open.

Conventional door opening mechanisms have left or right-sided hinges.These open in a sideways direction pivoting on a hinge which would pivotfrom a side edge. This conventional door opening mechanism leave theopened door in a position that could hinder access to the inside of thecabinet, especially in a narrow space, such as an alley, or leave thedoor in a position that could expose it to damage from other doors orequipment. Furthermore, hinging a door from the side could contribute todoor-sag from its own weight and dimensions. An additional issue facedwhen designing a fuel cell cabinet for outdoor operation is theintegrity of the weather seal at each door interface. The seal must bepositively assured in order to eliminate the reliability impact of waterand foreign material entry to the cabinet.

Referring to FIGS. 7-9, in one embodiment, the entire door 30 (e.g.,both the interior portion 32 and the outer portion 34) can be opened toaccess the interior of the enclosure or cabinet 10 of the module 12 or14. In order to mitigate the door-sag which might result from the torqueupon the door when it is opened, door structures of large stationarygenerators are generally significantly reinforced with expensive andcomplex structural members.

Another prior art door panel configuration involves removable cabinetdoors. With such designs, when a fuel cell system is being serviced, thedoor panel is removed and set to the side. In the case of large scalestationary fuel cell generators, removable doors are generally notemployed because lifting off a large and heavy door assembly wouldgenerally require two field service personnel.

According to an exemplary embodiment, the inner portion 32 and the outerportion 34 of the door 30 open in tandem with a substantially verticaland then substantially horizontal swing (e.g., “gull-wing” style). Inother words, the door 30 opens by being moved up and then at leastpartially over the top of the enclosure 10 in a substantially horizontaldirection. The terms substantially vertical and substantially horizontalof this embodiment include a deviation of 0 to 30 degrees, such as 0 to10 degrees from exact vertical and horizontal directions, respectively.

The door 30 is mounted on to walls of the enclosure or cabinet 10 of themodule 12 or 14 with plural independent mechanical arms, such as twoarms 50 and two arms 54. FIGS. 7-9 show one arm 50 and one arm 54 on theright side of the cabinet 10. The corresponding arms 50 and 54 on theleft side of the cabinet 10 are obscured by the right side arms and thusnot visible in the side views of FIGS. 7-9. Thus, in the non-limitingexample, two arms 50 and 54 are provided on either side of the door 30for a total of four arms.

The first arm 50 includes a first, generally straight end 51 and asecond, generally curved end 52. The second arm 54 includes a first,generally curved end 55 and a second, generally straight end 56. Thesecond arm 54 is longer than the first arm and has a more pronouncedcurvature at one end. The ends 51 and 55 are coupled to the interiorsurface of a wall of the enclosure 10 at a fixed distance relative toeach other. The ends 52 and 56 are coupled to the door 30 at a fixeddistance relative to each other. End 51 is located closer to the doorthan end 55. End 52 is located above end 56 on the door.

The angle of attack for the door 30 as it is opening and closing and achange in the vertical position when closed and horizontal position whenopen can be adjusted by changing the location of the pivot points on thedoor 30 and on the enclosure 10 or by adjusting the shape and/or lengthof the arms 50 and 54.

Biasing members 58, such as springs, may be added to assist in openingthe door, as shown in FIG. 9. The biasing members 58 are mounted in sucha way as to assist in the opening of the door 30 a slight distance whenthe latch is released (as described below) and continue assisting as thedoor 30 is fully opened. According to an exemplary embodiment, thebiasing members are coil springs. The coil springs are affixed to theenclosure 10 and connect to the arms 50 and 54. The coil springs are setto provide the correct lifting assist at different positions of the doorarms 50 and 54.

As shown in FIG. 8, in the open position, the arms 50 and 54 and thebiasing members 58 cooperate to hold the door 30 in a generallyhorizontal orientation above the enclosure 10. The movement of the door30 between the closed position (FIG. 7) and the open position (FIG. 8)as constrained by the arms 50 and 54 has several advantages over aconventionally side-hinged door. The hinge mechanism includes arelatively low number of parts. Site layout required (e.g., clearancerequired surrounding the enclosure) with the gull-wing door 30 issmaller than for side-hinged door of the same dimensions because of theshorter path traced by the door 30 as it opens compared to a path tracedby a side hinged door. When closing the door 30, the user is aided bygravity to overcome the force of the biasing members 58.

Further, in the open position shown in FIG. 8, the upper portion of thedoor 30 may be located over the enclosure or cabinet 10 and the lowerportion of the door may optionally overhang the opening to the enclosure10. In this configuration, the door 30 has the advantage of providingrain and snow protection for a user when open since the lower portion ofthe door overhangs from the fuel cell system enclosure 10.Alternatively, the entire door 30 may be located over the enclosure 10in the open position.

Door Latch Mechanism

Prior art door latch mechanisms of fuel cell system cabinets often makeuse of a small compression latch, typically attached directly to a key.In these, when the door is large, significant force must be applied tothe door in a “pushing” fashion in order to achieve gasket set and toallow the latch to close.

Referring now to FIGS. 10 and 11, a latch 60 for a door 30 is shownaccording to an exemplary embodiment. FIG. 10 shows the door 30 in theclosed and locked position with the outer door portion 34 madetransparent to show the latch 60 mechanism. FIG. 11 shows the door inthe closed and unlocked position with the outer door portion 34 notshown to expose the latch mechanism. Preferably, the latch is locatedinside the door 30 between the inner 32 and outer 34 door portions. Thelatch 60 for the door 30 includes a side handle 62, one or more biasingmembers (e.g., springs 58 shown in FIG. 9), a wheeled latch actuatingmechanism 64, an optional lock 66, and a catch 68 coupled to theenclosure 10 (e.g., to frame of cabinet 12 or 14). The handle 62 isprovided on the side of the door 30 (e.g., on the edge portion of thedoor 30 between the inner 32 and outer 34 portions of the door, suchthat the handle 62 is exposed from the side of the cabinet 12, 14). Thehandle 62 is hinged so that it can be swung out to the side of themodule 12 or 14. In other words, the user can swing or rotate the handle62 in a plane parallel to the front surface of the door (i.e., in aplane which extends between the inner 32 and outer 34 door portions).The handle 62 is directly or indirectly mechanically connected to themechanism 64 such that movement of the handle in a circular motion inthe above described plane causes the mechanism to slide to the side(i.e., left or right) to disengage or engage the catch 68.

To lock the door 30, the door is first swung back down into the closedposition, as shown in FIG. 7. The handle 62 is pulled down and to theleft (e.g., rotated in a clockwise motion) in a plane parallel to theimaginary plane between the inner and outer door portions, as shown inFIG. 10. As the handle 62 is pulled down and to the left side, causesthe wheeled latch actuating mechanism 64 to slide to the right sidealong the track until the mechanism 64 engages the catch 68. As thelatch mechanism 64 engages with the catch 68 which is coupled to theframe of the enclosure 10 (e.g., the frame of cabinet 12 or 14), thedoor 30 is pulled inward toward the enclosure 10, applying a “set” orfixed amount of compression to the door gasket. The positive “set” onthe gasket materials once the latch 60 is engaged helps the door seal tobe weather tight so that it may prevent entry of water (e.g., rain orsnow) or other foreign material into the enclosure 10. The latch 60 mayalso include a lock mechanism 66 which allows the door 30 to be lockedshut by the user using a key or other implement. To unlock the door 30,the user first unlocks the lock 66 with a key. The user then rotates thehandle counterclockwise (i.e., up and to the right) in the planeparallel to the imaginary plane between the inner and outer doorportions, as shown in FIG. 11. As the handle 62 is pulled up and to theright side, causes the wheeled latch actuating mechanism 64 to slide tothe left side along the track until the mechanism 64 disengages from thecatch 68. Once the mechanism 64 is disengaged from the catch 68, thedoor 30 is unlocked and can be swung up into the open position, as shownin FIG. 8. While the latch has been illustrated with movement in theleft, right, clockwise and counterclockwise directions, this should notbe considered limiting on the scope of the invention. Any other suitablemovement directions can also be used. For example, for the handle 62located on the left side of the door, the above directions are reversed.

In another exemplary embodiment, the latch 60 may include an electricalactuator to release the latch to allow the door to open. The electricalactuator can be configured to allow either remote control opening of thedoor 30 (by the remote monitoring command center), or opening of thedoor 30 by an encoded signal from a hand-carried device such as anelectronic key carried by a field service engineer.

Positioning Hot Box In Power Module

The internal components of the power module 12 may need to beperiodically removed, such as to be serviced, repaired or replaced.Conventionally, the components, such as the hot box or the balance ofplant components are removed from the power module 12 with a forklift.While conventional fuel cell assemblies may require substantial space onall sides to position a forklift and remove the components from anenclosure, sometimes as much as four to five times the length of the hotbox.

As shown in FIG. 12, a field replaceable fuel cell module (FCM) 70includes the hot box sub-system 13, such as the cylindrical hot box (seealso FIG. 1) which contains the fuel cell stacks and heat exchangerassembly, as well as a balance of plant (BOP) sub-system includingblowers, valves, and control boards, etc. The FCM 70 is mounted on aremovable support 72 which allows the FCM 70 to be removed from thepower module 12 cabinet as a single unit. FIG. 12 shows a non-limitingexample of a FCM 70 configuration where the FCM 70 includes acylindrical hot box 13 and a frame which supports the BOP components.The hot box and the frame are mounted on common support, such asfork-lift rails 72. Other configurations may also be used. For example,the hot box 13 may have a shape other than cylindrical, such aspolygonal, etc. The support 72 may comprise a platform rather thanrails. The frame may have a different configuration or it may be omittedentirely with the BOP components mounted onto the hotbox 13 and/or thesupport 72 instead. The FCM 70 is dimensionally smaller than the openingin the power module 12 (e.g., the opening closed by the door 30).According to an exemplary embodiment, the FCM 70 is installed or removedfrom the power module 12 cabinet as a single assembly. The FCM 70 iscoupled to the other components of the enclosure 10 using a minimalnumber of quick connect/disconnect connections (e.g., to connect to thewater conduits 28, fuel conduits 27, and bus bar conduits 24 housed inthe base 20) in order to ensure rapid servicing time, as described inthe prior embodiments.

Referring to FIGS. 13-16, a process for removing an FCM 70 from a powermodule 12 cabinet is shown according to an exemplary embodiment. The FCM70 and power module 12 are configured to allow the FCM 70 to be easilyremoved with a minimal amount of space around the power module 12needed. In this way, the enclosure 10 can require a much reducedfootprint relative to existing systems.

As shown in FIG. 13, a pallet 74 is placed next to an open power module12. The pallet 74 may be a simple metal pallet which allows mechanicallylifting the FCM 70 with attachment to the pallet 74. In otherembodiments, the pallet 74 may include a lead-screw type structure forpositively pulling the FCM 70 from the power module 12 cabinet.

As shown in FIG. 14, with the pallet 74 in place, the FCM 70 is removedfrom the interior of the power module 12. In one embodiment, rollers aredeployed from the FCM 70 and the FCM 70 rolls on guide rails out of thepower module 12. The FCM 70 may slide or roll on rollers which are fixedto the FCM 70 or roll on rollers which are fixed to the frame of thepower module 12. In another embodiment, the FCM 70 slides out of thepower module 12 using a lead-screw type structure. The motor structurefor the lead-screw for moving the FCM 70 in or out of the power module12 may be mounted either on the FCM 70 or on the power module 12cabinet. In still another embodiment, the FCM 70 may slide on aircushion similar to a device used to move sensitive semiconductor tooling(e.g., a hover-craft like device).

As shown in FIGS. 15 and 16, once the FCM 70 is clear of the powermodule 12 cabinet, it can be lifted and moved away from the power module12. The rails 72 are perpendicular to lift rails of the pallet 74,allowing the FCM 70 to be lifted by a forklift from either the sideusing the pallet 74 in a direction perpendicular to the extensiondirection in which FM rails, or the front using the FCM fork-lift rails72. Therefore, the space which must be reserved as service clearance forthe fuel cell enclosure 10 is reduced, as a fork-truck or pallet jack isnever forced to approach the power module 12 from a “head on” direction.Further, the sliding of the FCM 70 from the power module 12 usingrollers, a lead-screw, an air cushion or another suitable method allowsa single field service person to be able to load and unload FCM 70.

FIG. 23A illustrates an alternative removal tool 71 to a fork lift. Inthis embodiment, the removal tool 71 is a pallet jack which includesforks adapted to fit the rails of the moveable support 72. The palletjack includes a lifting mechanism to engage the forks of the pallet jackwith the rails of the movable support. After sliding the forks into therails, the forks are lifted until the weight of the movable support 72and the FCM 70 are supported by the forks. The movable support 72 maythen be rolled out of the enclosure 12 by the jack 71. Any suitablelifting mechanism may be used in the removal tool, such as mechanical orpneumatic lifting mechanisms

FIGS. 23B and 23C illustrate an exemplary embodiment of an alternativeremovable support 72. In this embodiment, the movable support 72includes air rollers located at the bottom of the movable support 72.Air rollers are a pneumatic device that include one or more air bladders75 operatively connected to retracted wheels/rollers 77. The air rollersare activated by attaching an air source (e.g., an air tank, not shown)to the air bladder. Air from the air source engages one or more airbladders 75, which in turn cause the wheels 77 to extend/lower from theretracted position. The wheels 77 may comprise conventional solid metalor plastic wheels which are pushed down out of the rails 72 by theinflation of the bladder 75. Alternatively, the wheels 77 may compriseinflatable wheels, rollers or tube made of an inflatable shell which isinflated with air from the air bladder 75 to form inflated rollers,wheels or tube. The inflated rollers, wheels or tube distribute theweight of the FCM over the entire base/rails 72 and span the gapsbetween the rails 72 and pallet 74. When the wheels 77 are extended, themovable support 72 (with the FCM attached) can be rolled or pulled outof the enclosure 10 onto the pallet 74 manually or using a pallet jack71 show in FIG. 23A.

Desulfurizer Assembly

Referring now to FIGS. 17-21, the input/output module 14 may include adesulfurizer assembly 80. The desulfurizer assembly 80 is provided inthe enclosure 10 for pre-processing of the fuel to reduce the amount oforganosulfur compounds and/or other impurities. Reducing organosulfurcompounds in the incoming fuel reduces contamination of the fuel cellsin hot box 13.

Prior art fuel cell systems often use two large, cylindricaldesulfurizer canisters in series. Each canister contains a desulfurizermaterial bed which removes sulfur from the inlet fuel stream beingprovided to the fuel cells. When the sulfur is expected to have brokenthrough the bed in the first canister, both canisters are exchanged fora new set of canisters or the desulfurizer material bed is replaced inboth canisters. However, the second canister or second desulfurizermaterial bed is replaced before being completely used up because thesecond bed still has the ability to adsorb more sulfur. In other words,as trace amounts of sulfur species begin to break through the first bed,the additional capacity to adsorb higher sulfur concentrations is neverutilized in the second bed. Thus, underused bed material is discarded,leading to a higher system cost.

Referring to FIG. 17, a desulfurizer assembly 80 includes four vessels82 (e.g., canisters, tanks, etc.) each containing a desulfurizationmaterial, such as zeolite, etc. beds. While four canisters 82 are shown,the assembly may contain any suitable number of canisters, such as two,three or more than four (e.g., five to eight). The incoming fuel inletstream for the fuel cells passes through the canisters 82 in series. Thecanisters 82 are arranged on a rotatable pad 84 that rotates about acentral axis 85. The rotatable pad 84 allows easy access and separateservicing of each canister 82 without disturbing the operation of theother canisters 82. Using four canisters 82 arranged as shown in FIG. 17allows for longer life and more complete utilization of bed materials inthe canisters than cascade arrangement of two beds or canisters.

The canisters 82 are generally rectangular prismatic bodies with abeveled edge 83. The beveled edge 83 helps to properly orient thecanister 82 on the rotatable pad 84. The beveled edge 83 further allowsfor better space utilization when rotating all four canisters 82together by eliminating a corner of the canister 82 that would otherwiseextend beyond the rotatable pad 84 and interfere with the rotation ofthe desulfurizer assembly 80. Tall, narrow canisters 82 allow for use ofa deeper, more narrow cabinet space in the input/output module 14.

Referring to FIGS. 18-21, each of the canisters 82 have four internalchannels 86 (e.g., subdivisions, chambers, etc.), with the fuel passingthrough each of the channels 86 in the canister 82 in fluid series(i.e., such that the fluid, such as a fuel inlet stream flows througheach of the canisters in series). The desulfurizer assembly 80 thereforeessentially has sixteen channels 86 in fluid series. The canister 82 isa low cost design which can be manufactured using extrusion methods. Therelatively large length/diameter ratio of the channel 86 increasesmaterial efficiency. The geometry of the channels 86 causes a moderatepressure drop and relatively uniform flow of the fuel inlet stream. Bulkmixing occurs at four points in each canister 82, reducing edge effectsand bypass.

The desulfurizer assembly 80 may further contain a sulfur sensor ordetector to detect sulfur that has broken through the final canister 82in the series. Having four canisters 82 in series allows for gassampling after each canister 82. According to an exemplary embodiment,the sulfur detector is a resistor connected between voltage or currentterminals. The resistor may comprise a metal strip or other conductorwhich has a reference resistance when new. The metal of the strip reactsin the presence of sulfur containing compounds, forming reactionbi-products such as metal sulfides, which have a higher electricalresistance. During operation of the assembly 80, a resistancemeasurement is made across the metal strip via a sensing circuit. Whenthe resistance begins to shift to a higher value, the sensor isproviding indication of the presence of sulfur. The detectors are placeddown-stream of one or more channels 86. As the sensors indicate thepresence of sulfur, the breakthrough of sulfur compounds can beinferred, allowing the operator of the fuel cell enclosure 10 toschedule a maintenance activity to exchange and rotate canisters 82.

All inputs and output (I/O) connections 88 for the canisters 82 areprovided on the same side (e.g., the top side) of the desulfurizerassembly 80. The I/O connections 88 are swiveling leak-tightconnections. Swiveling connections allows for the desulfurizer assembly80 to continue operating as it rotates about the central axis 85. Forexample, as shown in FIG. 22, the assembly 80 contains four canistersDES 801, DES 802, DES 803 and DES 804 and I/O connections 88, such asquick connects/disconnects 801 s to 815 s.

Each of the canisters 82 in series can absorb organosulfur compoundsuntil the saturation level results in organosulfur compounds escapingthe canister 82 without being absorbed. In normal operation of thedesulfurizer assembly 80, the first three canisters 82 in series areallowed to break through. Once a sulfur sensor detects organosulfurcompounds breaking through the third canister 82 in the series (e.g.,DES 803), the first canister 82 in the series (e.g., DES 801) isbypassed and then removed. The canister DES 801 may be bypassed byclosing connection 803 s-803 p and connecting connection 802 s toconnection 805 p. This way, the fuel inlet stream travels from the inletdirectly through connection 802 s-805 p into the second canister DES 802bypassing canister DES 801. Canister DES 801 is then removed from theassembly 80 to be refilled with fresh desulfurizer material. Thecanisters 82 are rotated 90 degrees so that the canister 82/DES 802 thatwas originally second in the series is placed in the first positionLikewise, the canister 82/DES 802 formerly third in the series is movedinto the second position and the canister 82/DES 804 formerly last inthe series is moved to the third position. A new canister 82 is thenplaced in the fourth position. The new canister may be connected intothe fourth position by having its inlet connected to connection 815 pand its outlet connected to connection 815 s while these two connectionsare bypassed. By doing this, each canister 82 is able to collect sulfureven after sulfur has broken through the third canister 82/DES 803.

Arranging the canisters 82 on a rotatable pad 84 avoids confusion bymaking rotation procedure a constant. The use of four canisters 82allows connections between middle canisters 82 in the cascade series toremain undisturbed while a spent canister 82 is being removed and a newcanister 82 installed. Because of the arrangement of the canisters 82 onthe rotatable pad 84, all four canisters 82 can be brought in closeproximity to the front of the module 14 cabinet (e.g., to within 14inches to meet UL requirements in the United States). The I/Oconnections 88 allow the inlet and the outlet plumbing to stay in thesame place while the canister 82 change their place in order.

While the desulfurizer assembly 80 described above includes loosedesulphurization material in a generally rigid canisters 82, in anotherexemplary embodiment, desulfurization material may be pre-loaded intogas permeable bags. Then, the packaging of the desulfurization materialinto the desulfurization canister 82 is simplified via loading the bagsinto the canister structure—thereby eliminating the need to pourmaterial into place. This further makes disassembly simpler because thebags may be quickly removed. Handles, ropes or other features might beattached to the bags to aid in removal of bags of spent material fromthe canisters 82. While a desulfurization assembly is described above,any other adsorption bed assembly other than a desulfurization assemblymay include a rotatable support and a plurality of vessels arranged onthe rotatable support, where each vessel contains an adsorption bed.

The construction and arrangements of the fuel cell system, as shown inthe various exemplary embodiments, are illustrative only. Although onlya few embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Someelements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process, logicalalgorithm, or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary embodiments without departing fromthe scope of the present disclosure. Any one or more features of anyembodiment may be used in any combination with any one or more otherfeatures of one or more other embodiments.

1. A modular fuel cell system, comprising: a base; at least one powermodule arranged in a row on the base; and a fuel processing module and apower conditioning module arranged on at least one end of the row on thebase; wherein: each power module comprises a separate cabinet comprisingat least one fuel cell stack located in a hot box; and the at least onepower module is electrically and fluidly connected to the fuelprocessing and the power conditioning modules through the base.
 2. Thesystem of claim 1, wherein the fuel processing and power conditioningmodules are located in a common input/output cabinet.
 3. The system ofclaim 1, wherein the fuel processing module is located in a firstcabinet and the power conditioning module is located in a second cabinetwhich is separate from the first cabinet.
 4. The system of claim 3,wherein the first cabinet, the second cabinet and each power modulecabinet have doors facing perpendicular to an axis of the row.
 5. Thesystem of claim 1, wherein the fuel processing module comprises at leastone adsorption bed and the power conditioning module comprises a DC/ACconverter, electrical connectors for AC power output and a systemcontroller.
 6. The system of claim 1, wherein each power, fuelprocessing and power conditioning module may be serviced, repaired orremoved from the system without opening the remaining module cabinets inthe system and without taking off line, servicing, repairing or removingthe other modules in the system.
 7. The system of claim 1, wherein thebase comprises a pre-cast concrete, geopolymer or steel base comprisingchannels which contain electrical bus bar conduits, input and outputfuel conduits and at least one water conduit which extend to the system,from the system, or between the modules.
 8. The system of claim 1,wherein the cabinet comprises: a cabinet housing; and a door in thehousing; wherein: the door comprises one or more inner portions and oneor more outer portions; and the outer portions may be opened while theinner portions remain closed or the outer portions comprises a differentmaterial than the inner portions.
 9. The system of claim 8, wherein: theinner portion forms a framework for the door and couples the door to thecabinet housing; and the outer portion is coupled to the inner portionand provides an outer fascia for the door.
 10. The system of claim 9,wherein the outer portion is formed of non-fire resistant polymermaterial and the inner portion is formed of a fire resistant materialselected from metal and fire resistant polymer material.
 11. The systemof claim 9, wherein the entire door is injection molded as a singlestructure made of different materials or is made by vacuumthermoforming, such that the inner portion is made from a heat and flameresistant plastic sheet, and the outer portion is made from a plasticthat is weather resistant and has a lower heat and flame resistance thanthe inner portion.
 12. The system of claim 8, further comprising atleast one air filter located in a space between the inner and outerportions of the door, such that the outer portion may be opened whilethe inner portion remains closed.
 13. The system of claim 12, wherein:the at least one filter comprises a plurality of the filters which arelocated over each other in the space between the inner and the outerdoor portions; the filters are supported on the inner surface of theouter portion; an edge of the door between the inner and outer portionscomprises an air inlet opening to the space between the inner and outerdoor portions; and the inner door portion includes an air outlet openinginto an interior of the cabinet.
 14. The system of claim 13, furthercomprising at least one perforated screen located in an air flow pathbetween the air inlet opening and the at least one filter; wherein: awidth of the space between the inner and outer door portions is largerthan that of the air inlet opening; and the space between the inner andouter door portions provides an air flow path comprising at least oneturn of at least 90 degrees between the air inlet opening and the atleast one filter such that debris in the air flow falls to a bottom ofthe space.
 15. The system of claim 1, wherein the base comprises two ormore pre-cast concrete or geopolymer sections.
 16. The system of claim1, further comprising an adsorption bed assembly, comprising: arotatable support; and a plurality of vessels arranged on the rotatablesupport, each vessel containing an adsorption bed.
 17. The assembly ofclaim 16, wherein: the assembly comprises a desulfurizer assembly forthe fuel cell system; the adsorption bed comprises a bed of at least oneof an impurity adsorption or desulfurization material; and the pluralityof vessels are connected in fluid series.
 18. The assembly of claim 17,wherein each vessel comprises a canister having a generally rectangularprismatic body with a beveled edge and a plurality of separate internalchannels and wherein all inputs and output connections for the pluralityof vessels comprise swiveling leak-tight connections arranged on thesame side of the assembly.
 19. The assembly of claim 17, furthercomprising a species sensor to detect sulfur or other contaminant thathas broken through a vessel in the fluid series.